chore: add a script to generate schema (#4248)

* chore: add a script to generate schema

* typo fix

* refactor

scripts/generate-schema.js

@@ -0,0 +1,102 @@
+#!/usr/bin/env node
+
+"use strict";
+
+const prettier = require("..");
+
+console.log(
+  prettier.format(
+    JSON.stringify(generateSchema(prettier.getSupportInfo().options)),
+    { parser: "json" }
+  )
+);
+
+function generateSchema(options) {
+  return {
+    $schema: "http://json-schema.org/draft-04/schema#",
+    title: "Schema for .prettierrc",
+    type: "object",
+    definitions: {
+      optionsDefinition: {
+        type: "object",
+        properties: options.reduce(
+          (props, option) =>
+            Object.assign(props, { [option.name]: optionToSchema(option) }),
+          {}
+        )
+      },
+      overridesDefinition: {
+        type: "object",
+        properties: {
+          overrides: {
+            type: "array",
+            description:
+              "Provide a list of patterns to override prettier configuration.",
+            items: {
+              type: "object",
+              required: ["files"],
+              properties: {
+                files: {
+                  description: "Include these files in this override.",
+                  oneOf: [
+                    { type: "string" },
+                    { type: "array", items: { type: "string" } }
+                  ]
+                },
+                excludeFiles: {
+                  description: "Exclude these files from this override.",
+                  oneOf: [
+                    { type: "string" },
+                    { type: "array", items: { type: "string" } }
+                  ]
+                },
+                options: {
+                  type: "object",
+                  description: "The options to apply for this override.",
+                  $ref: "#/definitions/optionsDefinition"
+                }
+              },
+              additionalProperties: false
+            }
+          }
+        }
+      }
+    },
+    allOf: [
+      { $ref: "#/definitions/optionsDefinition" },
+      { $ref: "#/definitions/overridesDefinition" }
+    ]
+  };
+}
+
+function optionToSchema(option) {
+  return Object.assign(
+    {
+      description: option.description,
+      default: option.default
+    },
+    option.type === "choice"
+      ? { oneOf: option.choices.map(choiceToSchema) }
+      : { type: optionTypeToSchemaType(option.type) }
+  );
+}
+
+function optionTypeToSchemaType(optionType) {
+  switch (optionType) {
+    case "int":
+      return "integer";
+    case "array":
+    case "boolean":
+      return optionType;
+    case "choice":
+      throw new Error(
+        "Please use `oneOf` instead of `enum` for better description support."
+      );
+    default:
+      return "string";
+  }
+}
+
+function choiceToSchema(choice) {
+  return { enum: [choice.value], description: choice.description };
+}